Water and energy are inextricably linked. Because thermoelectric generation and fossil fuel extraction can impact water resources, it is critically important to protect U.S. water supplies while providing the energy needed to power the nation in the 21st century. Through integrated water and energy-related activities, the U.S. Department of Energy/National Energy Technology Laboratory (DOE/NETL) Water-Energy Interface program has attempted to address this challenge through the development and application of advanced technologies and supporting science.

As U.S. population and associated economic development continue to expand, the demand for electricity increases. Thermoelectric generating capacity is expected to increase by approximately 6 percent between 2008 and 2035, according to projections from the Energy Information Administration's (EIA) Annual Energy Outlook 2010 (AEO 2010). Depending upon the assumptions invoked, water withdrawal to support electricity generation is expected to stay the same or decline slightly over the same time period. However, water consumption is expected to increase by anywhere from 14 to nearly 26 percent on a national basis.

Withdrawal is expected to remain the same or decrease because plants likely to be retired between 2005 and 2030 are older facilities that are more likely to employ high-withdrawal, once-through cooling. New facilities that will be built over that time period are likely to employ lower-withdrawal but high-consumption wet recirculating cooling systems. These projections are based on a business-as-usual approach, and do not reflect responses to potential greenhouse gas mitigation regulations.

A potentially influential factor in future water use in energy generation is carbon capture and sequestration (CCS). In fact, if coal is to remain an important component of energy production in the United States under any future climate/energy legislation, CCS will be essential. Carbon capture technologies that are commercially available (on a small scale) today typically consume large quantities of water, and could increase water consumption by 50 to more than 90 percent depending on the power generation platform.

The additional water required for a power plant with carbon dioxide (CO2) capture technology is largely due to the additional cooling water requirements used during capture and compression, thereby increasing the evaporative losses from the cooling tower. Given the factors noted above, coal-fired power plants may increasingly compete for freshwater with other sectors such as domestic, commercial, agricultural, industrial, and in-stream use – particularly in regions of the country with limited freshwater supplies. In addition, current and future water-related environmental regulations and requirements will challenge the operation of existing power plants and the permitting of new thermoelectric generation projects.

The interface of energy and water, or the water-energy nexus, can be defined as the many relationships between energy and water that are necessary to ensure an adequate supply of both resources for every purpose. Understanding the interlocking nature of water-energy interactions is the key to determining how to make the most efficient use of these critical resources, both for short-term economic benefit and for longer-term societal and environmental sustainability. A summary comparison of water and energy issues shows a striking correspondence between issues on the water side and issues on the energy side. The immediacy of these issues lends particular urgency to the effort to understand and manage the water-energy nexus.

Water Issues

Energy Issues

Rapidly growing demand for clean, fresh water is creating competition for limited water resources that may also limit energy production.

Steadily growing demand for energy requires greater water use and consumption of often scarce freshwater resources.

All regions of the United States are vulnerable to water shortages, particularly during periods of drought.

All regions of the United States are vulnerable to energy (electricity) shortages at times of peak demand.

Regional imbalances in water availability may require more energy to overcome.

Regional imbalances in electricity distribution may require more water in regions where energy is produced.

Water availability is usually dependent on electricity supply.

Electricity availability is usually dependent on water supply.

Fresh water sources are limited and require energy to transport, distribute, and deliver.

Supplies of readily accessible fuels are becoming depleted and require more energy to extract.

The regulatory framework for environmental protection against watershed incursions may require more energy.

The regulatory framework for environmental protection from power plant emissions requires more water, directly and indirectly.

Water sourcing, distribution, and use need to become more efficient.

Energy exploration, production, and use need to become more efficient.

To lower intensity of water use, non-consumptive uses of water need to be further explored.

To lower intensity of energy use, renewable and emerging energy resources need to be further explored.

The water infrastructure is aging, and its maintenance or replacement will require energy.

The energy infrastructure is aging, and its maintenance or replacement will require both energy and water.

The population is continuing to grow, increasing water demand.

The population is continuing to grow, increasing energy demand.

Long-term societal and economic sustainability of water resources and watersheds may require water use curbs.

Innovations for Existing Plants (IEP) Program has conducted an integrated research and development (R&D) effort directed at technologies and concepts to reduce the amount of freshwater used by power plants and to minimize any potential impacts of plant operations on water quality. The vision and mission for this effort is presented in the box below:

NETL Water-Energy Program Vision and Mission

Vision: A 21st century America that can count on abundant, sustainable fossil energy and water resources to achieve the flexibility, efficiency, reliability, and environmental quality essential for continued security and economic health.

Mission: To lead the critical national RD&D effort directed at removing barriers to sustainable, efficient water and energy use, develop technology solutions, and enhance understanding of the intimate relationship between energy and water resources.

The program is built upon partnership and collaboration with industry, academia, and other government and non-government organizations around four specific areas of research: